Implementation of the OPAC adaptive control strategy in a traffic signal network

The Real-time Traffic Adaptive Control System (RT-TRACS) represents a new, state-of-the-art system in advanced traffic signal control. It has been developed cooperatively by a team of U.S. academic, private and public researchers under the guidance of the Federal Highway Administration (FHWA). The system provides a framework to run multiple traffic control algorithms, existing ones as well as new adaptive algorithms. The OPAC (Optimized Policies for Adaptive Control) control strategy, which provides a dual capability of distributed individual intersection control as well as coordinated control of intersections in a network, is the first adaptive algorithm implemented within the RT-TRACS framework. OPAC was the first comprehensive strategy to be developed in the U.S. for real-time traffic-adaptive control of signal systems. This paper presents the operational features of the OPAC algorithm and describes the implementation and field testing of OPAC within the RT-TRACS system.